This invention relates to an electrode for a secondary battery having a high capacity and excellent charging and discharging characteristics. Further, it pertains to an electrode for a secondary battery which can constitute a cylindrical secondary battery as a flexible and coil-shaped electrode or a sheet-shaped secondary battery as a thin sheet-shaped electrode, particularly an electrode for a lithium secondary battery of which the active substance is lithium or an alkali metal composed mainly of lithium.
As the electrode for lithium secondary battery, it has been proposed to use an electroconductive polymer such as polyacetylene.
However, an electroconductive polymer is not sufficient in the doped amount of lithium ions, namely electrode capacity and stable charging and discharging characteristics.
Also, an attempt has been made to use lithium metal as the negative electrode of lithium secondary battery, but in this case, the charging and discharging cycle characteristics are not extremely good. More specifically, during discharging of the battery, lithium moves as lithium ions from the negative electrode body into an electrolyte, while during charging the lithium ions are again electrodeposited as metallic lithium onto the negative electrode. By repeating such charging and discharging cycle, the metallic lithium electrodeposited by accompaniment with such cycle becomes shaped in a dendrite. Since the dendrite-shaped lithium is a very active substance, it decomposes the electrolyte, thereby causing an inconvenience to occur that the charging and discharging cycle characteristics of the battery are deteriorated. Further, when this grows until the dendrite-shaped metallic lithium electrodeposited product reaches the positive electrode through the separator, there ensues the problem of causing short-circuit phenomenon to occur. That is, the charging and discharging cycle life is short.
For avoiding such problems, it has been attempted to use a carbonaceous material of a sintered organic compound as the negative electrode and carry lithium or an alkali metal composed mainly of lithium thereon. By this, the charging and discharging characteristics of the negative electrode could be dramatically improved, but on the other hand, an electrode molding material by use of this carbonaceous material is poor in flexibility, and no satisfactory electrode shaped in sheet or coil could be obtained.